On your Xbox.
On Xbox.com: [url="http://www.xbox.com/en-US/hub/reveal"]http://www.xbox.com/en-US/hub/reveal[/url]

From Major Nelson:

[quote]
[url="http://majornelson.com/2013/05/21/xboxreveal-day-where-to-watch/"]#XboxReveal Day: Where to watch [/url]
Watch the main event today at[url="http://www.timeanddate.com/worldclock/fixedtime.html?msg=%23XboxReveal&iso=20130521T10&p1=234&ah=1"] 1p ET/10a PT/17:00 GMT[/url] via the live global stream that will be available on Xbox LIVE and [url="http://www.xbox.com/hub/"]Xbox.com[/url]. If you are in the US or Canada, you can also watch the broadcast on Spike TV.
Note: The Xbox.com version should be viewable on most mobile devices.
If you have a If you have a Windows Phone 8, [url="http://www.windowsphone.com/en-us/store/app/live-video-player/0ae9f9fa-29b2-4318-845f-4e24ce52ca94"]download the free Live Event Player[/url] to view watch the stream.
The full show will be available later in the day for viewing via video on demand on Xbox.com and Xbox LIVE.
PLUS later today [url="http://www.timeanddate.com/worldclock/fixedtime.html?msg=Special+Twitch.TV+Broadcast&iso=20130521T12&p1=234&am=45"]at 3p ET/12n PT/19:00 GMT[/url] I am hosting a special #XbxoReveal recap show that will [url="http://www.twitch.tv/xbox"]ONLY be streamed on Twitch.tv[/url] During this time I